cluster/gce/gci/credential-provider: add unit tests for getCredentials()

Signed-off-by: Andrew Sy Kim <andrewsy@google.com>
Co-authored-by: Aditi Sharma <adi.sky17@gmail.com>

cluster/gce/gci/credential-provider/main_test.go

@@ -0,0 +1,55 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+type fakeTokenServer struct {
+	token string
+}
+
+func (f *fakeTokenServer) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	fmt.Fprintf(w, `{"access_token": "%s"}`, f.token)
+}
+
+func Test_getCredentials(t *testing.T) {
+	server := httptest.NewServer(&fakeTokenServer{token: "abc123"})
+	defer server.Close()
+
+	in := bytes.NewBuffer([]byte(`{"kind":"CredentialProviderRequest","apiVersion":"credentialprovider.kubelet.k8s.io/v1alpha1","image":"gcr.io/foobar"}`))
+	out := bytes.NewBuffer(nil)
+
+	err := getCredentials(server.URL, in, out)
+	if err != nil {
+		t.Fatalf("unexpected error running getCredentials: %v", err)
+	}
+
+	expected := `{"kind":"CredentialProviderResponse","apiVersion":"credentialprovider.kubelet.k8s.io/v1alpha1","cacheKeyType":"Registry","auth":{"*.gcr.io":{"username":"_token","password":"abc123"},"*.pkg.dev":{"username":"_token","password":"abc123"},"container.cloud.google.com":{"username":"_token","password":"abc123"},"gcr.io":{"username":"_token","password":"abc123"}}}
+`
+
+	if out.String() != expected {
+		t.Logf("actual response: %v", out)
+		t.Logf("expected response: %v", expected)
+		t.Errorf("unexpected credential provider response")
+	}
+}